I bought 6 glow light tetra's tonight and put them in my tank (75 gallon) in the store the fish had a pretty orange stripe, but in the tank the stripe is pretty much nonexistent, could this be my lighting? running 2-48" t5 HO's.

I'm not too familiar with tetras, but some fish lose their color when stressed, like moving them from one place to another. Once they've been in you tank a while their color should come back, but this is just a guess from my experience.